A few months ago, a few friends and I were debating the "smell of hot metal". We have all experienced it, but not quite sure what it would be. Certainly the surfaces we were thinking of aren't hot enough to actually boil off Fe ions. Our best guess was convection currents from the heated surface drawing organic molecules from the room and creating an aroma.

No, technically there's "no smell" because it's a vacuum. The article refers to the particulates that cling to the astronauts space suits, thus when they come back in and take them off it makes the place smell like that.

I'd think all those plastics and metals, in a vacuum and heated, would off gas just enough to gain their smell.Without air pushing the particles around, they would stick to the suit and follow you into the airlock.

/That and the microscopic bits of star stuff that are probably floating around out there./Tho a few atoms per cubic mile probably isn't enough to smell like anything.

mr_a:A few months ago, a few friends and I were debating the "smell of hot metal". We have all experienced it, but not quite sure what it would be. Certainly the surfaces we were thinking of aren't hot enough to actually boil off Fe ions. Our best guess was convection currents from the heated surface drawing organic molecules from the room and creating an aroma.

That would not seem likely in space.

Any thoughts?

If I had to guess -- and I obviously do -- I'd say it's probably mostly the smell of molecular oxygen reacting with the materials they have (spacesuits, tools). Unlike the O2 we're used to at ground level, molecular oxygen is highly reactive. Over time, it has a corrosive effect on stuff we put in space, which is one reason stuff won't last forever up there. Under the minimally filtered solar radiation at that extreme altitude, I imagine it might produce a distinctive smell of reacting molecules on and around the suits and tools. One of the modules on ISS is a Japanese experiment testing various materials' resilience to factors like that in low Earth orbit.

Sylvia_Bandersnatch:mr_a: A few months ago, a few friends and I were debating the "smell of hot metal". We have all experienced it, but not quite sure what it would be. Certainly the surfaces we were thinking of aren't hot enough to actually boil off Fe ions. Our best guess was convection currents from the heated surface drawing organic molecules from the room and creating an aroma.

That would not seem likely in space.

Any thoughts?

If I had to guess -- and I obviously do -- I'd say it's probably mostly the smell of molecular oxygen reacting with the materials they have (spacesuits, tools). Unlike the O2 we're used to at ground level, molecular oxygen is highly reactive. Over time, it has a corrosive effect on stuff we put in space, which is one reason stuff won't last forever up there. Under the minimally filtered solar radiation at that extreme altitude, I imagine it might produce a distinctive smell of reacting molecules on and around the suits and tools. One of the modules on ISS is a Japanese experiment testing various materials' resilience to factors like that in low Earth orbit.

And by 'molecular' oxygen I meant to say 'elemental' oxygen. O2 is molecular; O1 is elemental. Duhr, I need cawfee.

I've smelled something similar to what the astronauts describe upon opening a large vacuum chamber (part of a molecular beam epitaxy rig, so parts of it get a thin coat of vacuum-deposited metals every time it's used) to the atmosphere. I suspect that at least part of the smell comes from byproducts of the oxide coating forming on exposed metal surfaces, which would explain why welding creates a similar smell. In space, I imagine some of that oxide coating gets knocked off the metal by hard UV, so it would do something similar when it comes back into the atmosphere.

I'm not sure what byproducts would result from forming an oxide coating, though. Leftover single oxygen atoms, maybe? Those would probably stick to the nearest thing they find, so you'd actually be inhaling ozone or nitrous oxide, right? I know bare, oxide-less metal surfaces tend to do strange catalytic stuff too, so maybe there are more complicated products involved.

Professor Science:I've smelled something similar to what the astronauts describe upon opening a large vacuum chamber (part of a molecular beam epitaxy rig, so parts of it get a thin coat of vacuum-deposited metals every time it's used) to the atmosphere. I suspect that at least part of the smell comes from byproducts of the oxide coating forming on exposed metal surfaces, which would explain why welding creates a similar smell. In space, I imagine some of that oxide coating gets knocked off the metal by hard UV, so it would do something similar when it comes back into the atmosphere.

I'm not sure what byproducts would result from forming an oxide coating, though. Leftover single oxygen atoms, maybe? Those would probably stick to the nearest thing they find, so you'd actually be inhaling ozone or nitrous oxide, right? I know bare, oxide-less metal surfaces tend to do strange catalytic stuff too, so maybe there are more complicated products involved.

Cthulhu_is_my_homeboy:The Beatings Will Continue Until Morale Improves: I figured the "smell of space" was ozone from the heated air when the air lock is repressurized.Some of the suit material might be ionized as well.

Ozone has a really distinctive smell though. I wouldn't compare it to seared meat or hot metal.

I sort of like the smell of ozone. It always gives me a headache though.

Hollie Maea:Cthulhu_is_my_homeboy: The Beatings Will Continue Until Morale Improves: I figured the "smell of space" was ozone from the heated air when the air lock is repressurized.Some of the suit material might be ionized as well.

Ozone has a really distinctive smell though. I wouldn't compare it to seared meat or hot metal.

I sort of like the smell of ozone. It always gives me a headache though.

Thats because its incredibly toxic. Trust me, you don't want to be smelling ozone much.

Quantum Apostrophe:"Outer" space? They're still in our atmosphere and still experience 90% of our gravity field. They're just smelling their own suit being bombarded by particles.

The Kármán line largely defines the boundary between outer space and the atmosphere. It's 100 km up there. NASA and the US military use other definitions, but every definition of outer space I read includes the altitude of the ISS, which is 403 km.

After looking this up just now, I realize that you don't actually speak the same language as the rest of us. I mean, you use terms that others recognize, but you make up your own definitions at odds with commonly accepted use to provoke people.

I wish there was a term for that. Oh well. I'll upload my brain to a quantum computer and be exploring the galaxy as a robotic spacecraft in a half century. I imagine I mght actually miss these types of interactions, but maybe I can have the "nostalgia" subroutine left out of the final build.

This article, besides being 50 years late, is spectacularly silly. When it says space, it means the moon. Obviously we have not travelled anywhere else in order to sniff.The easiest analogy to process; the moon smells like the 4th of July at 11:30pm. Space has no odor at all.Talk about a sad, sorry news day.

BolloxReader:The Kármán line largely defines the boundary between outer space and the atmosphere. It's 100 km up there. NASA and the US military use other definitions, but every definition of outer space I read includes the altitude of the ISS, which is 403 km.

Wow, all the way up to the thermosphere! Well sheeit, I best put down a payment on my Mars condo quick-like!

As for your delusional claptrap in the rest of your post, I assume it pleases you to jest.